1. Field of the Invention
The present invention is concerned with an apparatus for the draining of rain water from roofs or the equivalent. The apparatus is based on the principle of providing closed flow in the vertical draining pipe at the dimensioned water quantity, so that the draining is intensified and smaller and less expensive conduits can be used as compared with pipe systems requiring mixed flow, in which, thus, both air and water flow.
2. Description of the Related Art
In the dimensioning of rain water pipes, different modes are in use in different countries, and for the dimensioning of the conduits, so-called dimensioning rainwater quantities have also been defined, the maximum intensity being, e.g., in Finland 150 l/s/ha (liters per second per hectare), in Sweden 130 l/s/ha, in Germany in certain places 400 l/s/ha.
It is known in the prior art to provide a closed flow, e.g., by fitting a so-called roof well inti the roof, into which the water flowing from the roof is collected and in whose bottom portion there is an opening for connecting the vertical draining pipe. The opening is covered by a solid cover, whose perforated edges have been bent downwards so as to form a water lock when the roof well is full of water. The objective is to prevent the access of air and the formation of a water vortex in the opening of the draining pipe (FI Pat. No. 41,451).
According to another suggested construction in the prior art, attempts are made to prevent access of air into the vertical draining pipe by placing a plug-like conical cover member in the mouth opening of the pipe whose shape corresponds to the air vortex of water when water rushes into an opening freely (FI Pat. No. 58,193).
Primary drawbacks of the prior art solutions are the high costs of roof wells, reduction in the thickness of the insulation, and, moreover, that the water is not drained uniformly. The water flows into the roof well rather uniformly, but is emptied from it unevenly. So-called swinging is produced when the water level in the roof well is alternatingly going up and down. The efficient draining caused by closed flow empties the roof well rapidly. Thereupon air is mixed with the water for some time, whereat the flow rate is reduced until the well is again filled, whereat access of air is prevented and closed flow starts again. The phenomenon is noticed as a disturbing water shock and as noise.